The construction industry is one of the largest consumers of natural resources, contributing significantly to global CO₂ emissions and waste generation. To address these environmental and economic challenges, the integration of circular economy principles into real estate development is essential. This thesis investigates how circular principles can be effectively incorporated into project selection processes, particularly in the transformation of existing buildings. The research aims to bridge the gap between circularity and standardized project evaluation methods to enhance sustainability while maintaining economic feasibility.

The study is guided by the central research question: "How can circular principles be integrated into project selection criteria in real estate development?" To address this, three sub-questions explore the principles of circularity, the criteria for project selection, and the development of a structured framework for implementation.

A mixed-method approach was employed, including an extensive literature review, semi-structured expert interviews, and a focus group workshop. The literature review provided insights into existing circular economy frameworks, project selection methodologies, and key drivers and barriers to circularity. Empirical research involved interviews with nine industry experts and a validation workshop with seven professionals, enabling a comprehensive analysis of practical challenges and enablers for circular transformation projects.

Findings highlight that economic feasibility remains a major barrier to circular transformations, with high upfront costs and regulatory constraints limiting adoption. However, tools such as Life Cycle Assessment (LCA), material passports, and digital tracking systems enhance transparency and facilitate informed decision-making. The study also emphasizes the importance of early integration of circularity in project selection, the role of expert knowledge and interdisciplinary collaboration, and the need for corporate cultural shifts to ensure long-term circular adoption.

Based on these insights, this research develops a structured roadmap to systematically embed circular principles into project selection processes. The roadmap aligns circular strategies with key decision-making stages, offering practical recommendations for real estate developers, policymakers, and investors. By balancing economic, environmental, and social objectives, this study contributes to advancing sustainable real estate practices and promoting a shift towards a circular built environment.

The Dutch Climate Act (2019) requires a substantial reduction in greenhouse gas (GHG) emissions, targeting a 49% reduction by 2030 and 95% by 2050. The construction sector, which is responsible for 15% of the Netherlands' CO2 emissions, largely relies on concrete, a material that contributes up to 8% of global CO2 emissions, primarily due to cement production. Transitioning to sustainable concrete is vital for meeting these climate targets. This study explores how demand-side organisations, particularly purchasers, can facilitate the adoption of green concrete in the Netherlands by establishing environmental standards and prioritising sustainable materials in construction projects.

This research utilises qualitative methods, including literature reviews, stakeholder interviews, and case studies of both conventional and green concrete projects. The findings emphasise the importance of promoting the 'cement with purpose' concept, generating demand for near-mature innovations, providing extensive testing for emerging innovations, and contributing to the development of alternative materials beyond slag. At the project level, the successful adoption of green concrete is associated with clear sustainability targets, strong engineering capabilities, client willingness to accept risks, and the strategic use of pilot projects.

The study proposes a conceptual framework, the Green Concrete Adoption Strategy for Purchasers (GCAS-4P), which combines strategic and practical insights to assist demand-side organisations in advancing the green concrete transition. It also highlights the need for further research to consider supplier perspectives and broader regional transitions.

In the last years, municipalities' role in protecting cities from climate change impacts has increasingly gained attention due to their proximity to the citizens. Although municipalities have the tools to implement mitigation and adaptation strategies, anchoring these strategies will demand multiple interventions in the urban sphere if municipalities execute all these projects through a siloed approach. Multi-interventions will increase energy consumption, generating more C02 emissions, as well as more mobility disruptions. Therefore, municipalities need to design and execute their projects integrally. Through a literature review and Rotterdam Municipality serving as a case study, this research explores both the theoretical and practicality of how municipalities can effectively apply an integrated infrastructure design approach (IIDA) to enhance climate-resilient infrastructures (CRI). The research found some of CRI's key characteristics and seven implementation lenses of IIDA at the municipal level: functional, transdisciplinary, synergistic, intervention scale, technological, time and finance.
Furthermore, a thematic analysis of 22 interviews revealed 19 key factors that influence a municipality's effectiveness in using an integrated design approach. These factors were grouped into six dimensions: human capacity, organisational culture, governance, information and knowledge, project process development, and finance. These findings have been translated into a strategic roadmap, providing practical guidance for municipalities to effectively implement IIDA.
The roadmap suggests municipalities need individuals with soft skills such as holistic vision, proactivity, and collaboration. Additionally, fostering an innovative and collaborative culture is essential to enable the development of pilot projects. From the knowledge generated from pilot projects, municipalities can update their standards process.